Paving machines are used to apply, spread and compact a “mat” of material relatively evenly over a desired surface. These machines are used regularly in the construction of roads, parking lots and other areas where a smooth durable surface is required for cars, trucks and other vehicles to travel. An asphalt paving machine, for example, generally includes a hopper for receiving asphalt material from a truck and a conveyor system for transferring the asphalt rearwardly from the hopper for discharge onto a roadbed. Transversely-disposed screw augers may be used to spread the asphalt material transversely across the roadbed in front of a screed plate. The screed plate smoothes and somewhat compacts the asphalt material and ideally leaves a roadbed of uniform depth and smoothness.
In order to help achieve the desired uniform depth and smoothness as well as to accommodate different job site conditions and different desired roadbed configurations, the screed assembly can include a variety of adjustments. These adjustments can be used to vary, for example, the width and thickness of the mat as well as the degree of any crown. Such an auger arrangement is disclosed, for example, in Chinese Publication CN1070707A, which discloses a plurality of parallel augers that may be individually clutch controlled to provide a desired thickness and width of paving material. Providing a desired thickness of the mat may be more difficult during wide width paving, however, inasmuch as the material demands may be different through the length of the screed because of varying job site conditions and desired roadbed configurations. That is, some areas along the length may require more material, while other areas require less.
Some paving machines may be adapted to provide a wider span of material by the addition of screed plate and auger extensions. Presently, however, only left and right halves of auger, including the extensions, can be independently controlled. Accordingly, present arrangements may not be sufficient for distributing varied amount of paving material along the entire length of a screed and may lead to overfill in some regions of the road surface. For example, the amount of material distributed may be high in the center of the screed, low in the middle of the left side of the screed and high at the end of the screed. Turning the entire auger, i.e., both left and right halves or all the sections of the auger, may force material into the low filling portion, but may also force more paving material towards the ends of the screed. Thus, this delivery of material may cause an over fill of the paving material on the road surface on the side receiving an excess of material at the end of the screed. It would be desirable to provide an arrangement that would permit an operator to distribute paving materials in a manner consistent with a desired road surface.